1. Systems of Measurement
Chapter 3
Systems of Measurement
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2. Metric System
The metric system is the most common and the only standardized system
Adopted in 1799 in France
Most precise
Based on powers of 10
3 parameters associated with Rx and administration of meds weight, length, and volume
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3. Metric System Weight is the most utilized; the base for weight is gram
Volume will usually be in reference to liquids and base unit is liter
Length is the least utilized measurement but will be used often to measure height and base unit is meter; most used will be cm (centimeters) and mm (millimeters)
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4. Metric Prefixes Micro = one millionth or 0.000001 or of the base unit
Milli = one thousandth or or of the base unit
Centi = one hundredth or 0.01 or of the base unit
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5. Metric Prefixes (Continued)
Deci = one tenth or 0.1 or of the base unit
Kilo = one thousand or 1,000 times the base unit
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6. International System (SI) of Metric Units and Abbreviations
Weight
Gram (base unit) – g
Milligram – mg
Microgram – mcg (µg)
Kilogram – kg
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7. International System (SI) of Metric Units and Abbreviations
Volume
Liter (base unit) – L (ℓ)
Milliliter – mL (mℓ)
Cubic centimeter – cc
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8. International System (SI) of Metric Units and Abbreviations
Length
Meter (base unit) – m
Centimeter – cm
Millimeter – mm
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9. Comparing Common Metric Units
PREFIX
Kilo-
Hecto-
Deca-
BASE
Deci-
Centi-
Milli-
Decimilli-
Centimilli-
Micro-
Weight
kilogram
gram
milligram
microgram
Volume
liter
deciliter
milliliter
Length
meter
centimeter
millimeter
Value to Base
1,000
100 10
1.0
0.1
0.01
0.001
0.0001
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© 2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

10. Remembering Order GRAM LITER METER kilo hecto deca BASE deci centi
milli K H D C M
“King
Henry
Died
from a
Disease
Called
Mumps”
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11. k h d (BASE) d c m BASE is meter, liter, or gram
BASE is the only letter that can stand alone
To convert metric to metric, use the supplied chart
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12. k h d (BASE) d c m k h d Base d c m
To convert 1 gram to centigram, you move the decimal as you would in the chart
k h d Base d c m
So 1 gram = 1.00 = 100 centigrams
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13. Rules of Metric Notation
Unit or abbreviation always follows amount
5 g NOT g 5
Decimals used to designate fractional metric units
1.5 mL, NOT mL
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14. Rules of Metric Notation
Use a zero to emphasize decimal point for fractional metric units less than 1
0.5 mg, NOT .5 mg
Will prevent potential dosage error
If 5 mg was misinterpreted for 0.5 mg, the dosage would be 10 times too much and could be lethal
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15. Rules of Metric Notation
Omit unnecessary zeros
1.5 g, NOT 1.50 g
This is a critical rule
When in doubt, double-check
Ask writer for clarification
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16. Metric Measurements and Equivalents
Weight
Unit
Abbreviation
Equivalents
gram g
1 g = 1,000 mg
milligram mg
1 mg = 1,000 mcg = g
microgram
mcg
1 mcg = mg = g
kilogram kg
1 kg = 1,000 g
k h d Base d c m
Check these by using this chart
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17. Metric Measurements and Equivalents
Length
Unit
Abbreviation
Equivalents
meter m
1 m = 100 cm = 1,000 mm
centimeter cm
1 cm = 0.01 m = 10 mm
millimeter mm
1 mm = 0.001m = 0.1 cm
k h dk Base d c m
© 2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

18. Metric Measurements and Equivalents
Volume
Unit
Abbreviation
Equivalents
liter
L (or ℓ)
1 L = 1,000 mL
milliliter
mL (or mℓ)
1 mL = L = 1 cc
cubic centimeter cc
1 cc = 1 mL = L
k h dk L d c m cc
Again, this chart really helps
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19. Unsafe Abbreviations
Many health organizations have prohibited the use of “cc” as it has been confused with zeros and units
Micrograms should always be abbreviated “mcg” not “µg”
The word “unit” must be spelled out; it cannot be abbreviated “U”
Review CAUTION blocks in your book for more information
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20. Units Standardized amount needed to produce a desired effect
Used to measure unit of potency
Vitamins
Chemicals
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21. Milliequivalents (mEq)
One thousandth of an equivalent weight of a chemical
Used when referring to serum electrolytes
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22. Household System of Measurement
Unit
Abbreviation
Equivalents
drop
gtt
teaspoon
t (or tsp)
tablespoon
T (or tbs)
1 T = 3 t
ounce (fluid)
fl oz
2 T = 1 oz
ounce (weight) oz
1 lb = 16 oz
cup
1 cup = 8 oz
pint pt
1 pt = 2 cups
quart qt
1 qt = 4 cups = 2 pt
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23. Approximate Equivalents
1 t = 5 mL
1 T = 3 t = 15 mL = ½ fl oz
1 fl oz = 30 mL = 6 t
1 L = 1 qt = 32 fl oz = 4 cups
1 pt = 16 fl oz = 2 cups
1 cup = 8 fl oz = 240 mL
1 kg = 2.2 lb
1 in = 2.5 cm
© 2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.